Dual gripper picker assembly for an automated storage system

ABSTRACT

An automated storage system uses a pass-through picker assembly interposed between a storage device and a plurality of storage cells, wherein the pass-through picker assembly is mounted on an accessor and incorporates independently operating fore and aft grippers driven by a single motor. The fore and aft grippers are tandemly mounted such that the fore gripper can be aligned to one of a plurality of storage cartridges located with the storage cells, and the aft gripper can be aligned with a storage slot of the storage device. The pass-through picker design allows the fore gripper to grasp a storage cartridge, feed the cartridge through to the aft gripper, release, and then allow the aft gripper to grip and pass the storage cartridge to the storage slot. In this way, a special priority cell of the storage cells, directly across from the storage slot, can very quickly pass a priority storage cartridge directly to the storage device without moving the pass-through picker assembly.

FIELD OF THE INVENTION

The present invention relates generally to robotic handling systems, andmore particularly, to a storage system having a picker assembly forpassing a storage medium through the picker and into the storage device.

BACKGROUND OF THE INVENTION

Many business and science applications use computers to record data,with much of the data being stored on removable media. The removablemedia may take the form of a magnetic tape cartridge, an optical diskcartridge, floppy diskettes, or floptical diskettes. The advantages ofstoring data on removable media are numerous. These advantages include acapability of storing large amounts of data (additional cartridges canbe used to store additional data), providing a vehicle for long termstorage and archival, backing up data which resides on non-removablemedia, and allowing for easy transfer of data between computers. Oftenthe removable media is the most economical method of retaining thestored data.

In the past, when a request for a specific removable media cartridge wasmade, an operator needed to retrieve the data cartridge and physicallyload the cartridge into the storage device. This manual mode involved asignificant delay while the cartridge was being retrieved by theoperator before the data on that cartridge could be processed.Additionally, the operator could easily make an error and load anincorrect cartridge.

With advancements in data storage products, the media cartridges werereduced in size and robots were designed and incorporated toautomatically retrieve cartridges and load those cartridges into astorage device. The robot is housed within an automated storage librarythat also contained storage devices and a plurality of cartridges placedwithin storage cells. The robot replaced the operator and improvementswere seen in access time and in reliability. However, because the robotis a complex machine requiring multiple degrees of freedom (rotation andtranslation about the mechanical Joints) it would require maintenanceand adjustments. The robot's complexity also resulted in a significantmanufacturing and maintenance costs.

The difficulties that exist with the multiple degrees of freedom withina robot have been addressed, to some degree, by using a pass-throughpicker. The pass-through picker is the assembly that retrieves acartridge from a storage cell and places the cartridge into the storagedevice. The pass-through picker assembly is positioned within anautomated storage system between the storage device and the storagecells. The storage cells are typically located parallel to and oppositethe storage device. The pass-through picker retrieves a cartridge fromthe storage cell, passes the cartridge through its structure, andtransfers the cartridge to the storage device. Although this reduces thecomplexity of the picker as compared to a robot, the pass-through pickerlimits the location of the storage cells to being opposite the storagedevice. As data storage products further progress, this limitation doesnot allow for the total number of storage cells to be maximized withinthe automated storage system. Additionally, there is an ever increasingneed to provide still greater amounts of storage capabilities in smallerspaces. Therefore, the pass-through picker in combination with thestorage device and storage cells should use space very efficiently.

What is needed is a pass-through picker having the capability toretrieve cartridges from storage cells that are located both oppositeand adjacent to the storage device. This improvement would allow for thevolume of the automated storage system to be populated with a maximumnumber of storage cells, and maintain a relatively simple mechanism ascompared with a robot. Furthermore, if the pass-through picker assemblywere capable of transferring a cartridge into the storage device withoutdisturbing a cartridge that was directly opposite a load slot of thestorage device, then a cartridge could be located directly opposite thestorage device and the access time to load that cartridge would beminimal.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved pickermechanism for transporting storage media.

Another object of the present invention is to provide an automatedstorage system having a picker mechanism that can randomly accessstorage media while minimizing time to access such storage mediums andminimizing space required by the picker mechanism.

According to a first embodiment of the present invention, a pickerassembly for transporting a storage medium from a storage cell to astorage device and vice versa, includes a mounting channel having a foregripper and an aft gripper mounted parallel thereto, wherein the foreand aft grippers are located in tandem with one another. A cam motorconnects to the fore and aft grippers for closing the fore gripper andopening the aft gripper when rotating the cam motor in a firstdirection, and for closing the aft gripper and opening the fore gripperwhen rotating the cam motor in an opposite direction. A belt motordrives belts of the fore and aft grippers for moving a gripped storagemedium from the fore gripper to the aft gripper when the belt motor isrotated in a first direction, and for moving the storage medium from theaft gripper to the fore gripper when said belt motor is rotated in asecond direction.

In another embodiment of the present invention, a method fortransporting an article from a first location to a second location,wherein a picker mechanism having independently operating fore and aftgrippers mounted in tandem on a mounting channel for securing, moving,and releasing the article, is utilized. The method includes the stepsof: (a) moving the picker assembly to the article for locating thearticle between the fore gripper; (b) gripping the article by closingthe fore gripper; (c) moving the article out of the first position andinto an intermediate position between the fore and aft grippers; (d)opening the fore gripper; (e) transporting the picker mechanism formoving the article adjacent to a second position; (f) re-gripping thearticle by closing the aft gripper; and (g) moving the article into thesecond position and opening the aft gripper.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial diagram of an automated storage system havingmagazines containing removable media, a storage device, and a pickerassembly with two tandem, independent grippers.

FIG. 2 is a side view of the automated storage device illustrating apicker assembly utilizing a fore and aft gripper.

FIG. 3 is a perspective view of the picker assembly showing the beltdrive train.

FIG. 4 is a perspective view of the picker assembly depicting themechanism used to actuate the fore and aft grippers.

FIG. 5 is a side view of the picker assembly positioned at the magazineto retrieve a cartridge.

FIG. 6 is a side view of the picker assembly illustrating the foregripper in the closed position.

FIG. 7 is a side view showing the cartridge transferred to the center ofthe picker assembly, with the fore gripper in a closed position.

FIG. 8 is a side view of the picker assembly carrying a cartridge,wherein both fore and aft grippers are in the open position allowing thepicker assembly to be translated to the storage device.

FIG. 9 is a side view depicting the picker assembly at the storagedevice with the aft gripper closed.

FIG. 10 is a side view showing the cartridge transferred from the pickerassembly into the storage device, with the aft gripper closed.

FIG. 11 is a side view of the picker assembly that shows the aft gripperopen and the cartridge released into the storage device.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the illustrations, like numerals correspond to likeparts depicted in the figures. The invention will be described asembodied in an automated magnetic tape storage system for use in a dataprocessing environment. Although the invention is shown using magnetictape cartridges, one skilled in the art will recognize that theinvention equally applies to optical disk cartridges. Furthermore, thedescription of an automated magnetic tape storage system is not meant tolimit the invention to data storage applications as the inventiondescribed herein can be applied to robotic handling systems in general.FIG. 1 shows an automated storage system 1 for managing removable media,for example magnetic tape. The removable media is contained within aplurality of data cartridges 5. Each data cartridge 5 is located withina magazine 4, wherein each magazine 4 includes a plurality of storagecells for holding the plurality of data cartridges 5. The magazine 4provides a means of retaining each data cartridge 5 while also allowingaccess to retrieve the plurality of data cartridges 5 via a pickerassembly 3.

The automated storage system 1 also includes at least one storage device2, for example an IBM 3494 Magnetic Tape Drive. The magazine 4 islocated across from and parallel to the storage device 2. A magazine mayalso reside parallel and adjacent to the storage device 2 (not shown).The picker assembly 3 transports a data cartridge 5 from the magazine 4to a storage slot in the storage device 2. The picker assembly 3 isattached to an accessor 6 that translates the picker assembly parallelto the storage device 2 and magazine 4. This translation allows thepicker assembly 3 to be positioned directly in line with any of theplurality of data cartridges 5 and/or the storage slot.

Upon being positioned in line with a selected data cartridge 5, thepicker assembly 3 retrieves the data cartridge 5 from the magazine 4.The data cartridge 5 is retained within the picker assembly 3 while thepicker assembly 3 is translated to the storage device 2 via the accessor6. At the storage device 2, the picker assembly 3 transfers the datacartridge 5 into the storage device 2. After the storage device 2 hasprocessed the data cartridge 5, the picker assembly 3 removes the datacartridge 5 from the storage device 2 and is translated back to theoriginating storage cell (or an empty storage cell) within the magazine4, where the picker assembly 3 transfers the data cartridge 5 back intothe magazine 4.

Referring now to FIG. 2, a tandem relationship of fore and aft grippers20 and 21, respectively, of the picker assembly 3 is shown. The foregripper 20 faces the magazine 4, and the aft gripper 21 faces thestorage device 2. The tandem relationship of the fore gripper 20 to theaft gripper 21 enables a data cartridge to "pass-thru" the pickerassembly 3, hence the picker assembly 3 operates an a pass-thru picker.Both the fore and aft grippers 20, 21 extend beyond an envelope of thedata cartridges 5 when a data cartridge 5 is present on either side ofthe picker assembly 3. For the picker assembly to be translated, thefore and aft grippers must be in an open position (as shown) to avoid aninterference with any residing data cartridges 5. Note that by operatingthe fore and aft grippers 20, 21 independently, a distance separatingthe magazine 4 from the storage device 2 can be minimized since the foregripper 21 can be held open except when grabbing a data cartridge 5.Additionally, there is no need to translate the picker assemblyperpendicular to the storage device 2 and the magazine 4.

In order to retrieve a data cartridge 5 from the magazine 4 or thestorage device 2, the appropriate fore or aft gripper 20, 21 must closeand contact the given data cartridge. The picker assembly 3 describedherein allows for the fore and aft grippers 20, 21 to operateindependently, i.e., the fore gripper 20 can be maintained in an openposition while the aft gripper 21 is actuated open or closed, or viceversa. A benefit realized by independent gripper operation is that agiven data cartridge can be retrieved or returned by the picker assembly3 without disturbing other data cartridges 5.

FIG. 3 shows the picker assembly 3 in greater detail, including thosecomponents used to independently drive the fore gripper 20 and the aftgripper 21. Both fore and aft grippers 20, 21 are affixed to a mountingchannel 30 (mounting structure). Each fore and aft gripper 20, 21consists of a timing belt 34 and 38, respectively, mounted within asupport channel 35 and 39, respectively. Each timing belt 34 and 38provide a friction drive to translate the data cartridge 5 between thefore and aft grippers 20, 21. An opposing side of each fore and aftgripper 20, 21 includes a plastic guide 36 and 41, respectively, thatcontains a free-rotating roller 37 and 40, respectively. A single motor43 is centrally located between the fore and aft grippers 20, 21 forproviding a rotational drive for both timing belts 34 and 38 via apinion 31 and gears 32 and 33. A circuit card 42 acts as an interconnectto provide power to the motor 43 (and to a fore and aft gripper motor)and to provide signal lines to various sensors pairs 44 & 45.

FIG. 4 depicts a reverse side of the picker assembly 3, and containsthose components that actuate the fore gripper 20 and the aft gripper21. The fore gripper 20 includes the timing belt 34 and support channel35 that are connected to a plastic guide 36 by an upper linkage 47 and alower linkage 46. An extension spring 55 provides tension between theupper and lower linkages 47, 46. Opposite ends of the upper and lowerlinkages 47, 46 share a common pivot shaft 50 and a roller bearing 57.The aft gripper 21 design and construction is similar to the foregripper 20. By rotating a cam 54 that is centrally located between thetandem fore and aft grippers 20, 21, one of the two pivot shafts 50 or51 will translate horizontally and actuate the appropriate fore or aftgripper 20, 21 open and closed. A motor 52 and cam 53 provide amechanism for rotating the cam 54. The cam 54 profile will actuate thefore gripper 20 when the cam 54 is rotated ninety degrees whilemaintaining the aft gripper 21 in an open position, or vice versa.Consequently the tandem fore and aft grippers 20, 21 can be actuatedindependently to grip a data cartridge 5 on one side of the pickerassembly 3 without disturbing a data cartridge 5 that resides on theopposite side of the picker assembly 3.

METHOD OF OPERATION

Referring again to FIG. 1, the function of the picker assembly 3 is totransfer a data cartridge 5 from the magazine 4 to the storage device 2,and subsequently return the data cartridge 5 to the originating storagecell within the magazine 4. The operation sequence begins when a requestis sent to the automated storage system 1 to load into the storagedevice 2 a specific data cartridge 5 located within the magazine 4. Theinitial state of the picker is with the fore gripper 20 and the aftgripper 21 both in the open position, allowing the picker assembly tofreely traverse the magazine 4. The accessor 6 will translate the pickerassembly to be in line with the storage cell known to contain therequested data cartridge 5.

FIG. 5 is a side view of the picker assembly 3 when it has beentranslated to the position of the requested data cartridge 5. The cam 54is in an initial position that sets the fore gripper 20 and the aftgripper 21 both in the open position. In this condition, the fore pivotshaft 50 and the aft pivot shaft 51 are positioned furthest from thecam's center of rotation, resulting in the tandem fore and aft grippers20, 21 being open.

The next step in the operation sequence is depicted in FIG. 6. The cam54 has been rotated ninety degrees clockwise by the cam motor 52 (asviewed from the motor's shaft end). The cam's rotation allows the forepivot shaft 50 to move nearer to the cam's center. In this case the forepivot shaft 50 has moved to the right from its originating position inFIG. 5. The extension spring 55 provides tension between the upperlinkage 47 and the lower linkage 46. This tension exerts a force uponthe fore pivot shaft 50, to which the upper and lower linkages 47, 46are connected, and keeps the fore roller bearing 57 in contact with thecam 54. As the fore pivot shaft 50 moves nearer the cam 54 center, theupper and lower linkages 47, 46 pivot together, causing the timing belt34 and the lower plastic guide 36 to close and grip the data cartridge5. The cam 54 profile is such that an aft pivot shaft 51 and rollerbearing 58 remain stationary and the aft gripper 21 remains in an openposition.

FIG. 7 illustrates the data cartridge 5 when it has been transferredfully into the picker assembly 3, that is the data cartridge 5 rests inthe mounting channel 30. After the fore gripper 20 has closed and thetiming belt 34 has contacted the surface of the cartridge, the timingbelt 34 is rotated by the belt motor 43. The timing belt 34 acts as afriction drive to translate the data cartridge 5 from its initialposition in FIG. 6 to the center of the picker assembly 3. The datacartridge 5 is driven into the mounting channel 30 until the datacartridge 5 is positioned between two infrared sensor pairs 44 and 45.

Referring to FIG. 8, a next operation stage is opening the fore gripper20 to allow the picker assembly 3 to be translated to the storage device2. The fore gripper 20 is opened by rotating the cam 54 ninety degreescounterclockwise via the cam motor 52. The cam 54 rotation will forcethe fore pivot shaft 50 to move further from the cam 54 center as theroller bearing 57 follows the cams's profile. As the fore pivot shaft 50is translated the upper linkage 47 and the lower linkage 46 pivot open,whereby the fore gripper 20 opens. Both the fore timing belt 34 and theaft timing belt 38 contact the cartridge 5 at each timing belt 34, 38inner pulley. This contact occurs regardless of whether the fore and aftgripper 20, 21 is in an open or closed position. The contact serves asretention for the cartridge within the picker assembly 3 as the pickerassembly 3 is translated by the accessor 6. The retention prevents thecartridge from accidentally being Jostled loose of the picker assembly3.

FIG. 9 depicts the picker assembly 3 when its has been translated inline with the storage slot of the storage device 2. The cam 54 has beenrotated ninety degrees counterclockwise by the cam motor 52, resultingin the aft pivot shaft 51 moving nearer to the cam's center. In thiscase the aft pivot shaft 51 has moved to the left of its originatingposition in FIG. 8. An extension spring 56 provides tension between anupper linkage 48 and a lower linkage 49, keeping the aft roller bearing58 in contact with the cam 54. As the aft pivot shaft moves nearer thecam's center, the upper and lower linkages 48, 49 pivot together,whereby the timing belt 38 and the lower plastic guide 41 close andcontact the data cartridge 5. Again, the cam 54 profile is such that thefore pivot shaft 50 and roller bearing 57 remain stationary and the foregripper 20 remains in an open position.

Referring to FIG. 10, the data cartridge 5 has been translated outtowards the ends of the aft gripper 21. With the aft gripper 21 closed,the timing belt 38 has been driven by the belt motor 43, translating thecartridge to the position shown. The data cartridge 5 would now resideprimarily within the storage device 2 (not shown).

FIG. 11 shows the final step in transferring a cartridge from themagazine 4 to the storage device 2. The cam 54 has been rotated ninetydegrees clockwise by the cam motor 52. The aft pivot shaft 51 moves outfrom the cam 54 center as the roller bearing 58 follows the cam 54profile. As the aft pivot shaft 51 is translated the upper linkage 48and the lower linkage 49 pivot open, whereby the aft gripper 21 opens.The data cartridge 5 is no longer restrained by the picker assembly 3,and can be loaded into the storage device 2. While the data cartridge 5is being processed, the picker assembly 3 may reside in line with a loadslot of the storage device or may be used for transferring cartridges toother storage devices located within the same automated storage system,returning to the given storage device 2 when processing has beencompleted.

To return the data cartridge 5 from the storage device 2 to itsoriginating storage cell in the magazine 4, the sequence illustrated inFIG. 5 through FIG. 11 is reversed. First the data cartridge 5 would beretrieved from the storage device 2 using the aft gripper 21, thentransferred into the picker assembly 3. Once the data cartridge 5 iswithin the picker assembly 3, the picker assembly 3 can be translated tothe originating storage cell within the magazine 4, whereupon the foregripper 20 can be utilized to place the data cartridge 5 back into themagazine 4.

The picker assembly described herein provides a method to transport adata cartridge from a magazine to a storage device by implementing twotandem, independent grippers. Although the fore and aft grippers utilizea common motor to actuate each gripper, and a common motor to transferthe cartridge into the picker assembly, the two grippers can be actuatedindependent of one another. For example, the fore gripper can beactuated open or closed while the aft gripper remains open. Theadvantage gained by this method of operation is the capability to haveusable magazine storage cells aligned and on each side of the pickerassembly. Consequently the total storage capacity (number of storageslots) within an automated storage system can increase and fully utilizethe available volume within the system.

In summary, an automated storage system for randomly selecting onestorage medium from a plurality of storage media and transporting theselected storage medium therefrom has been described. The automatedstorage system includes a storage device for receiving the selectedstorage medium for retrieving data therefrom and/or storing datathereto.

A plurality of storage cells store the storage medium therein, theplurality of storage cells located across from and substantiallyparallel to the storage device. The storage media are oriented in theplurality of storage cells for direct transport to the storage device. Apicker mechanism, has first and second grippers mounted in tandem suchthat the first gripper has access to the storage media, and the secondgripper has access to the storage device. The first and second grippersfurther pass the selected storage medium therebetween, wherein the firstand second grippers each have open and closed positions, the first andsecond grippers maintaining opposite open and closed positions. Anaccessor is positioned for carrying the picker mechanism and moving thepicker mechanism between one of the plurality of storage cells and saidstorage device.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention. For example, various changes may be made to certain materialsas long as the critical requirements are met, for example, weight,strength, etc. Still further, means for attaching structures togethermay be changed without departing from the scope of the invention.

What is claimed is:
 1. A method for transporting an article from a firstlocation to a second location using a pass-thru picker mechanism havingfore and aft grippers mounted in tandem on a mounting channel forpassing the article therethru, said method comprising steps of:(a)moving the pass-thru picker assembly to the article such that thearticle is located partially within the fore gripper; (b) gripping thearticle by closing the fore gripper; (c) moving the article out of thefirst location and into an intermediate location between the fore andaft grippers; (d) opening the fore gripper; (e) transporting the pickermechanism for moving the article adjacent to the second location; (f)re-gripping the article by closing the aft gripper, while the foregripper remains open; and (g) moving the article into the secondlocation and opening the aft gripper.
 2. The method according to claim 1further comprising a step (h) of turning a motor in a first directionfor closing the fore gripper while the aft gripper remains open.
 3. Themethod according to claim 2 further comprising a step (i) of turning themotor in a second direction for opening the fore gripper and closing theaft gripper.
 4. The method according to claim 3 wherein the fore and aftgrippers are in an open position when the article is in the intermediateposition.
 5. A picker assembly having first and second openings and amounting channel therebetween for receiving an article into the firstopening, through the mounting channel, and into the second opening, saidpicker assembly comprising:a first gripper at the first opening forgripping the article and moving the article substantially through thefirst gripper; a second gripper at the second opening, the secondgripper located in tandem with the first gripper, the second grippergripping the article in the mounting channel, and moving the article outof the mounting channel and substantially through the second gripper;and a first motor coupled for independently opening and closing thefirst and second grippers.
 6. The picker assembly according to claim 5wherein the first and second grippers are mounted parallel to themounting channel.
 7. The picker assembly according to claim 6 furthercomprising a second motor for moving the article substantially throughsaid picker assembly.
 8. The picker assembly according to claim 7wherein said first motor closes the first gripper while the motor isrotated in a first direction, and the first motor closes the secondgripper while the first motor is rotated in a second direction.
 9. Thepicker assembly according to claim 8 wherein the first motor opens thefirst gripper while the motor is rotated in the second direction, andthe first motor opens the second gripper while the motor is rotated inthe first direction.